Washing machines are well known in the art. Commercial washing machines, in particular, may be used to clean a large volume of soiled fabrics, garments and linens (referred to collectively in this application as "garments"), or may be used by garment manufacturers to process large lot quantities of garments to remove fabric sizing, to dye, and to produce a "stone washed" effect by agitation in the presence of mechanical or chemical agents.
Conventional washing machines are commonly constructed using two cylindrical drums in which a movable perforated drum is placed within a stationary, watertight drum. Such interior perforated drums are generally rotated about a central axis and may contain vanes or other structures for agitating clothing. During the wash cycle, water is introduced into the water tight drum and passes through the perforations into the interior drum where the garments are placed for washing. When the appropriate amount of water has been delivered, a sensing mechanism switches off the valve between the water source and the washing machine and switches on an electric motor or other such means for rotating the interior drum. Agitation of the water and garments is usually accomplished by slowly rotating or moving the interior drum. When the wash cycle is complete, a switching device opens a valve at the lowest point on the watertight drum, and the water drains out by gravity or is pumped out using a vacuum pump. To aid in further removal of excess water from the garments, a spin cycle is often provided in which the inner drum is rotated about the axis of rotation at a high speed in one direction; the garments are forced against the wall of the perforated drum and excess water is forced from the garments through the perforations and into the stationary watertight drum by centrifugal force, where it drains by gravity or is pumped from the drum. In garment manufacturing, many such cycles can be used to process garments; for example, garments may be washed once to remove fabric sizing, a second time to dye the garments, and yet a third time to chemically or mechanically process the garments. To produce "stone washed" garments, the interior of the drum in such commercial washing machines may be provided with an abrading surface or chemicals may be introduced to give the garments the softer and slightly faded "stone washed" appearance.
Such two drum conventional washing machines are, however, difficult to empty of the garments, particularly when the washing machines are commercial washing machines having a large capacity, such as would be used by garment manufacturers. The machines are also difficult to clean because the perforated, rotating drum is not usually removable, so that the interior portions of the watertight drum are not accessible. Thus, residual amounts of dye or chemicals may remain which could interfere with subsequent wash cycles involving new batches of garments. Further, such machines use more water, detergent, dye and chemicals than are really needed because the vertical space between the two tanks must be filled before the wash solution will enter the perforated tank to wash the garments. Finally, in order to dry the garments cleaned in such machines, it is generally necessary to remove them from the washing machine and place them in a separate mechanical dryer which tumbles the damp garments in a stream of hot air until they are dry. This removal step, particularly for garment manufacturers processing large volumes of garments, unnecessarily consumes manufacturing time and floor space.
Because of the simplicity of construction, desirability of access to the interior of the sealed drum, and smaller water and washing chemical requirements, attempts have been made to construct single, water impermeable drum washing machines. See, for example, U.S. Pat. No. 2,397,268 to Jorgenson et. al. and U.S. Pat. No. 2,434,570 to Leef. However, these machines cannot extract excess wash or rinse water from garments as efficiently as the two drum machines, necessitating longer drying times.
Therefore a need exists for a commercial, single drum washing machine which can wash or process garments using only the minimum amount of water needed to wash the garments and which can then extract waste wash and rinse water from the garments as efficiently as a two drum washing machine. A further need exists for a commercial, single drum fabric finishing machine which can process, wash and completely dry garments in one operation.